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  1. MariaDB Server
  2. MDEV-7949

Item_field::used_tables() takes 0.29% in OLTP RO

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Details

    • Bug
    • Status: Closed (View Workflow)
    • Major
    • Resolution: Fixed
    • 10.1(EOL)
    • 10.1.9
    • OTHER
    • None

    Description

      Data comes from Sandy Bridge system running sysbench OLTP RO in 1 thread against 1 table.

      Call graphs:

      -   0.29%  mysqld  mysqld
         - Item_field::used_tables() const
            + 16.02% Item::const_item() const
            + 13.23% JOIN::prepare(Item***, TABLE_LIST*, unsigned int, Item*, unsigned int, st_order*, bool, st_order*, Item*, st_order*, st_select_lex*, st_select_lex_unit*)
            + 11.63% Item_func::update_used_tables()
            + 8.13% JOIN::optimize_inner()
            + 6.51% build_equal_items_for_cond(THD*, Item*, COND_EQUAL*, bool)
            + 5.63% st_select_lex::update_used_tables()
            + 5.11% setup_fields(THD*, Item**, List<Item>&, enum_mark_columns, List<Item>*, bool)
            + 5.03% Item_equal::update_const()
            + 4.33% Item_equal::update_used_tables()
            + 4.08% Item_func::fix_fields(THD*, Item**)
            + 4.07% Item_func::eval_not_null_tables(unsigned char*)
            + 3.44% Item_equal::fix_fields(THD*, Item**)
            + 2.52% JOIN::optimize()
            + 1.96% Arg_comparator::cache_converted_constant(THD*, Item**, Item**, Item_result)
            + 1.43% Item_sum::check_sum_func(THD*, Item**)
            + 1.42% make_join_statistics(JOIN*, List<TABLE_LIST>&, st_dynamic_array*)
            + 1.11% add_key_fields(JOIN*, key_field_t**, unsigned int*, Item*, unsigned long long, st_sargable_param**)
            + 0.77% setup_conds(THD*, TABLE_LIST*, List<TABLE_LIST>&, Item**)
            + 0.75% Item_func_between::fix_fields(THD*, Item**)
            + 0.74% Item_sum::update_used_tables()
            + 0.66% is_local_field(Item*)

      This is virtual method which can't be inlined. Most time spent for function call convention. Check if we can revoke it's virtual status.

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            sanja Oleksandr Byelkin
            svoj Sergey Vojtovich
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            Dates

              Created:
              Updated:
              Resolved:

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